The present invention generally relates to a method of attaching a sensing device to a substrate and, more specifically, a method of attaching a sensing device to a substrate to allow relative movement between the sensing device and the substrate after the sensing device is attached.
Low pressure sensors such as fuel tank pressure transducers are typically mounted to the substrate to which they are attached in a way that will allow slight relative movement between the sensor and the substrate. This is due to the fact that sensors of this type are very sensitive to stresses and strains which can affect the accuracy of the sensor, or cause damage to the sensor. Additionally, in order for the sensor to operate correctly, the sensor must be mounted at a specific distance from the substrate. Conventional methods of mounting such sensors to a substrate include using complex equipment to maintain the sensor at a distance while the adhesive being used to mount the sensor cures, or by using time and pressure placement solutions which have low capability. One specific conventional method involves placing glass beads within a thermal adhesive to maintain a standoff distance between the sensor and the substrate during curing of the adhesive, however, there is a need in the industry for an improved method of attaching a sensing device, such as a fuel tank pressure transducer, to a substrate, such as the interior of an automobile gas tank, at a specific distance from the substrate.
In accordance with an aspect of the present invention, the method for attaching a sensing device to a substrate at a pre-determined distance from the substrate preferably includes providing a compliant adhesive, depositing a first layer of the compliant adhesive onto the substrate, curing the first layer of the compliant adhesive, depositing a second layer of the compliant adhesive directly onto the first layer of the compliant adhesive, inserting the sensing device into the second layer of the compliant adhesive, and curing the second layer of the compliant adhesive.